It has long been desired to reduce both the drying time of coating compositions, especially for use as traffic paints, and, for environmental reasons, the content of volatile organic components (VOC) in them (The permissible amount of VOC that can be released in the air in the United States from traffic paints is expected to drop to less than 150 grams of VOC per liter of paint). However these two attributes are in conflict because replacing VOC with water generally increases drying time, especially under ambient high humidity conditions, which typically vary in the range of from 65 percent to 90 percent.
Improving the drying speed of aqueous compositions has been attempted, e.g. in EP-A 7210003, by adopting a two-stage approach wherein a layer of aqueous polymer is first applied, followed immediately by the application of thickener to accelerate its drying. However this approach is cumbersome and the two-stage, twin pack approach it demands fails to meet the third desirable attribute of coating compositions, namely that they be easy to apply.
This invention addresses the problem of reducing the VOC content of coating compositions which remain quick to dry and easy to apply in a single step by conventional single stage application means, such as air-atomized spray, airless spray, air-assisted airless spray, and high volume low pressure spray.